A stuffed bear pokes out from the snow at a makeshift memorial in Sandy Hook, after the December 14 shooting tragedy when a gunman shot dead 20 students and six adults at Sandy Hook Elementary, in Newtown, Connecticut, December 28, 2012. (Photo : Reuters)

A lone gunman killed 20 schoolchildren and six adults in an early morning rampage using semi- automatic weapons he had taken from his mother's house. But children and teachers throughout the school were able to hear the killings over the school's intercom system.

The lawyer, Irving Pinsky of New Haven, is filing the lawsuit against the school district claiming his client suffered emotional and psychological trauma and injury while waiting out the shooting.

Pinsky insists the lawsuit aims to improve school security. "It's about living in a world that's safe," Pinsky told The Associated Press on Saturday. "The answer is about protecting the kids."

"We all know it's going to happen again," Pinsky said. "Society has to take action."

Usually, states have immunity against the majority of lawsuits, unless they allow a particular lawsuit to proceed, so Pinsky is petitioning the state of Connecticut. So far, there is no word from the state.

The Newtown shooting has prompted soul searching and myriad proposals for reducing the number of mass shootings in America.

Since the Sandy Hook shootings, a gunman went on a rampage in rural Pennsylvania, and a sniper lured firefighters to a building he had set on fire before ambushing them, killing two.

Before that, there had been at least eight mass shootings in 2012, including a racially motivated attack at a Sikh temple in Wisconsin that left six dead, a workplace shooting in Minnesota that left five dead, and the shootings at a movie theater premiere in Aurora, Co. that left 12 people dead.

Mental health advocates are calling for better care for potentially violent people, while gun control advocates are calling for a ban on assault weapons and stricter background checks.

The National Rifle Association, after staying silent for a week after the Newtown shootings, held a press conference advocating armed guards in all schools in the country, a proposal quickly slammed by nearly every other interested party.